Strap forming apparatus



Nov. 27, 1956 v. A. NELSON 2,772,088

STRAP FORMING APPARATUS Filed July 18, 1955 IN VEN TOR.

Vic foruq. Ncl son geni' United States Patent STRAP FORMING APPARATUS Victor A. Nelson, Portland, Oreg.

Application July 18, 1955, Serial No. 522,563

4 Claims. (Cl. 270-93) This invention pertains to strap forming apparatus, and relates particularly to apparatus for folding a continuous strip of flexible sheet material into multiple layers to form a reinforced strap.

The present invention is particularly adapted to the production of a reinforced strap formed by the multiple folding of a continuous strip of paper or similar flexible sheet material, for the preparation of strap handles for merchandise containers. Such straps are applied, for example, to collapsible cartons and bags.

Apparatus provided heretofore for the production of such strap material have not been completely satisfactory because of serious limitations of speed and precision of folding, difficulties in threading and feeding the material through the apparatus, tendencies of the flexible material to develop undesirable creases during folding, and a tendency of the sheet material to tear as it progresses through the folding apparatus. These disadvantages are particularly evident in the use of arcuate formers, wherein the folding operations create stresses in the sheet material of suflicient magnitude to cause warping and tearing of the material at production speeds commensurate with economical operation.

It is a principal object of the present invention to provide strap forming apparatus which overcomes the disadvantages enumerated above and permits a speed of production substantially greater than afforded heretofore.

Another important object of this invention is the provi sion of strap forming apparatus which is of simplified construction for economical manufacture, which is precise in operation and is operable with speed and facility.

Other objects and advantages of the present inveniton will appear from the following detailed description, taken in connection with the accompanying drawings in which:

Figure l is a fragmentary plan view of strap forming apparatus embodying features of the present invention;

Figure 2 is a fragmentary line 22 in Figure l;

Figure 3 is a fragmentary sectional view taken along line 3-3 in Figure l and showing a preferred form of means by which to provide the final fold in the sheet material;

Figure 4 is a fragmentary foreshortened plan view of the sheet material, as viewed from the bottom in Figure 2, and showing said sheet material in successive stages of folding; and

Figure 5 is a foreshortened sectional view on an enlarged scale taken along the line 5-5 in Figure 4 and showing the sheet material in its final state of folding.

In the embodiment illustrated, the strap forming apparatus includes a supporting frame which comprises a pair of spaced parallel rails 14), 12. At the infeed end of this frame is a guide roll 14 provided at its end with projecting annular shoulders 16. The guide roll is supsectional view taken along ice ported for rotation between the rails 10, 12 by means of the stub shafts 18.

Extending transversely between the side rails adjacent the guide roll 14 is a pair of scoring rolls 20, 22, which are supported in cooperative opposing relation, as indicated in Figure 2. Roll 20 is provided with laterally extending stub shafts 24 which are mounted in bearings secured resiliently to the rails by means of the springs 28 which surround the mounting bolts 30. Roll 22 is provided with laterally extending stub shafts 32 which are supported in bearings 34 secured firmly to the side rails.

Roll 20 is provided with a plurality of grooves 36 which are arranged in predetermined spaced relation along the axis of the roll. Roll 22 is provided with a plurality of outwardly extending annular ridges 38 which are arranged in the predetermined spaced relation of the aforementioned grooves 36, for cooperative registration therewith. The grooves and ridges are made progressively wider toward the longitudinal center of the rolls 20 and 22, respectively, for purposes explained more fully hereinafter.

The continuous strip 40 of flexible sheet material, such as paper employed in the production of a reinforced strap, is supplied from a stock roll (not shown) and fed over the guide roll 14 between the projecting lateral shoulders 16 and thence between the cooperating rolls 20, 22. Here the strip of flexible material is subjected to the pressure of said rolls and, upon passing therebetween, it is scored along the predetermined fold lines by the cooperative action of the annular ridges 38 and grooves 36. These score lines thereby define longitudinal fold sections. The center fold section is identified by the reference numeral 42 and the pairs of sections spaced progressively outward on opposite sides of the center section are identified by the reference numerals 44, 44, 46, 46, 48, 48', and 5t), 50.

The scored flexible material then passes over a bending roll 52 which is mounted transversely between the side rails 10, 12 for rotation on stub shafts 54. The bending roll terminates at its ends on the outwardmost score lines, whereby to cause the outwardmost longitudinal sections 5%], 50, of the sheet material to bend downwardly (Figure 2). These outward sections then engage the laterally spaced folding members 56, 56, respectively, which extend inwardly from the side rails and are firmly secured thereto by means of the bolts 58.

Each of the folding members 56, 56, comprises an elongated section which extends substantially parallel to the side rails and are formed with a reverse twist throughout its length. Thus, as the flexible material travels toward the outfeed end of the apparatus, the outwardmost sections Si), 50', are caused to be folded under and to underlie the next outwardmost sections 48, 48'. These sections then are pressed together by passing the sheet material under the pressing roll 60 which is mounted for rotation transversely between the side rails 19, 12 on the stub shafts 62.

The flexible material is then passed over the second bending roll 64 which is mounted transversely between the side rails for rotation on stub shafts 66. The longitudinal ends of roll 64 terminate on the second outwardmost pair of score lines, whereby to cause the longitudinal sections 48, 58' to be bent downwardly. The flexible material then passes along a second pair of folding members 6 68, secured to the side rails by bolts '70. Thus, the sections 48, 48', are folded under, with the previously folded sections 50, 55' in abutment with the under side of the next outward sections 46, 46'. The folded sections are pressed together by passing under the pressing roll 72 which is supported transversely between the side rails for rotation on stub shafts 74.

The flexible material is then passed over a third bending roll 76 which extends transversely between the side rails 10, 12 and is mounted for rotation on stub shafts '78. The outer ends of pressing roll 76 terminate on the next outwardmost pair of score lines,'whereby to cause the longitudinal sections 46, 46 to be bent downwardly; These sections are folded under as they pass forwardly between the spaced folding members 8'9, 80' secured to the side rails by the bolts 82. Thus, as the sections 46, 46 are folded under, the previously folded sections 48, 48' are brought into abutment with the under surface of sections 44, 44, respectively. These sections are pressed together by passing the flexible material under the pressing roll 84 which is mounted transversely between the side rails for rotation on the stub shafts 85.

The flexible material is then passed forwardly over bending roll 88 which is mounted transversely between the side rails for rotation on stub shafts 90. This latter bending roll terminates at its longitudinal ends on the innermost pair of score lines, whereby to cause the innermost pair of longitudinal sections 44, '44 to be bent in- Wardly.

The final folding operation is achieved by passing the strip of material between an overlying press roll 92 and a pair of underlying folding elements 9 96. Each of these folding elements comprises a wire rod which is secured at one end .to one of the side rails by means of a bolt 98. The rod-is bent intermediate its ends arcuately upward and rearward, i. e., in the direction of the infeed end of the apparatus. These arcuate sections engage the downwardly bent sections 44, 44 of the strip and fold them under.

The press roll 92 is mounted for rotation on shaft 100 which is carried on one end of a lever arm 102, the opposite end of which is secured pivotally to side rail 10 by means of pivot bolt 104. The press roll 92 preferably is provided with a concave surface, as shown. By this construction the press roll functions in cooperation with the folding elements 94, 96 (Figure 3) to insure maximum folding of the multiple sections underlying the finally folded sections 44, 44.

It is to be noted from Figure that as the sections of flexible material are coiled outwardly from the center, the thickness of the fold lines progressively increase. Accordingly, the grooves 36 and ridges 38 are made progressively wider toward the center of the rolls 20, 22, re-

* spectively, as previously mentioned, in order to provide score'lines of progressively increased width and thus prevent tensioning at the folded edges of the strip, which otherwise would tend to unfold the strap.

The finally folded flexible material is then passed between a cooperating pair of press rolls 1%, 1&3 which are mounted for rotation transversely between the side rails 10, 12. Press roll 106 is provided at its ends with projecting annular shoulders lit) to guide the folded strap from the press roll 92.

Roll 106 is mounted by means of stub shafts 112 in bearings 114, which are mounted resiliently on the side rails by means of the springs 116 encircling the securing bolts 118. Roll 103 is secured firmly to the side rails for rotation on stub shafts 120, by means of bearings 122.

In order to facilitate the threading of the folded sheet material through the press rolls 1%, 108, there is provided means for separating said rolls. In the embodimcnt illustrated, this means comprises a pair of cam members 124 mounted for eccentric rotation on the stub shafts 120 and interconnected at their rearward ends by operating handle 126. The cam 124 are arranged to engage the stub shafts 112 and to elevate the latter, and hence the upper press roll 106, as the handle 126 is rotated in the clockwise direction as viewed in Figure 2.

in the operation of the apparatus described hereinbeforethe various stages of folding are accomplished without creating undesirable stresses in the flexible material which, in conventional strap forming devices, produce undesirable creases and cause frequent tearing. The folding operations are made gradually and smoothly, thereby aflording a speed of production heretofore not attainable. The apparatus is of simplified construction, requiring a minimum of maintenance.

It will be apparent to those skilled in the art that various changes may be madein the details of construction described hereinbefore without departing from the scope and spirit of the present invention. Further, it will be evident that the apparatus may be employed with various types of flexible material, such as paper, plastic sheeting and metal foil. Accordingly, it is to be understood that the foregoing description is primarily illustrative of the invention and is not to be considered as limiting the scope thereof.

Having now described my invention and the manner in which the same may be used, what I claim as new and desire to secure'by Letters Patent is:

1. Apparatus for folding a continuous strip of flexible material, comprising, an elongated frame extending substantially in a straight line and having an infeed end and an outfeed end, scoring roll means adjacent the infeed end of the frame for scoring the flexible material longitudinally along laterally spaced lines arranged on opposite sides of the center line of the material, whereby to form elongated sections of said material arranged in pairs on opposite sides of said center line, a plurality of bending means mounted on the frame and spaced progressively from the outfeed side of-the scoring roll means toward the outfeed side of the frame, each progressive bending means functioning to bend each progressively inwardly spaced pair of elongated sections of said material along the associated scoring lines, and folding means mounted on the frame adjacent the outfeed side of each bending means for folding the associated bent sections adjacent the next inward pair of sections, the scoring roll means being proportioned and arranged in such manner that the score lines of each of the'respective pairs of scorings are made progressively wider from the outer edge of the material toward the center line of the material whereby to accommodate the progressively increased thickness as the sections are overlapped.

2. The apparatus of claim 1 wherein the plurality o bending means comprises a plurality of rollers which are progressively shorter in length, the ends thereof terminating on the progressively inwardly spaced pairs of scor- 1 ing lines.

3. The apparatus of claim 1 wherein the folding means comprises a pair of inwardly directed members each havmaterial, comprising an elongated frame extending substantially in a straight line and having an infeed end and a outfeed end, scoring roll means adjacent the infeed end of the frame for scoring the flexible material longitudinally along laterally spaced lines arranged on opposite sides of the center line of the material, whereby to form elongated sections of said materialarranged in pairs on opposite sides of said center line,a plurality of bending means mounted on the frame and spaced progressively from the outfeed side of the scoring roll means toward the outfeed side of the frame, each progressive bending means functioning to bend each progressively inwardly spaced pair of elongated sections of said material along the associated scoring lines, folding means mounted on the frame adjacent the outfeed side of each bending means for folding the associated bent sections adjacent the next inward pair of sections, the folding means adjacent the outfeed end of the frame comprising a pair of 5 wire members secured to and extending inwardly from References Cited in the file of this patent the frame adjacent the outfeed end of the latter, the wire UNITED STATES PATENTS members bemg bent arcuately outward and upward, and a cooperating press roll mounted on the frame and register- 2,331,067 YmlPg 1943 ing with the wire members, the press roll having a con- 6 2349056 Sara May 1944 cave surface adapted to engage the surface of the folded FOREIGN PATENTS flexible material and to press the latter toward said wire members, 224,237 Great Britain Feb. 26, 1925 

